This invention relates to a process for producing L-alanine enzymatically. According to the present invention, L-alanine can be produced in high yield with good efficiency.
L-alanine, as is well known in the art, is an important amino acid. It is used as a starting material for pharmaceuticals and foods and has other uses in the chemical industry. Its demand has abruptly increased in recent years.
For the industrial production of L-alanine, there has been proposed primarily a process for producing it by enzymatic decarboxylation of L-aspartic acid (Japanese Patent Publication No. 27792/1978) or a process for producing it from fumaric acid and ammonia by permitting aspartase (EC 4.3.1.1) and aspartate .beta.-decarboxylase (EC.4.1.1.12) to act on these materials (Japanese Provisional Patent Publication No. 35991/1981). However, in the former process, L-aspartic acid which is the starting material is costly, resulting in higher production cost, while in the latter process, the optimum conditions such as pH and temperature in which both enzymes act are different, and therefore it is required that separate reaction tanks be used. Also, although both of enzymes can act in neutral pH, in that case, if microorganism cells or treated product thereof are used as the source of both enzymes, it is necessary to deactivate the enzyme presenting these materials which racemizes L-alanine co-present, and carry out the reaction at a relatively lower temperature (see Japanese Provisional Patent Publications No. 132882/1982, No. 87088/1987).